Dysfunction of the autonomic nervous system is an under-recognized but important aspect of the etiological and clinical manifestation of neuromuscular disorder such as Duchenne muscular dystrophy (DMD). DMD is an X-linked inherited disorder that affects over nearly 30 out of every 100,000 boys born in the United States. The disorder results from a defect in the gene for an enormous protein called dystrophin, which forms part of the scaffold in muscle fibers. Although the disorder is present from the initial stages of fetal development, there is no physical indication at birth that the baby is abnormal. Rarely is there physical diagnosis in the first year of life. Problems are usually not evident until 18 months to 4 years of age. Usually diagnosis is not made until the child is five. Nearly 50% of affected boys do not walk until 18 months of age or later. Duchenne children have difficulty climbing and getting up from the floor. Parents often comment that their child falls frequently. By the age 3 to 5 years, generalized muscle weakness becomes more obvious. Parents may be falsely encouraged by a seeming improvement at school age, but this may be due to natural growth and development. Weakness progresses rapidly after age 8 or 9, resulting in the inability to walk or stand unassisted. Leg braces may make walking possible for a year or two, but by early adolescence walking becomes impossible. There are some boys with Duchenne muscular dystrophy who have problems with delay in mental or language development. Eventually all the major muscles are affected. Lung capacity may decrease, resulting in an increased susceptibility to respiratory infections. Cardiac and respiratory failure are common in Duchenne patients.
Autonomic nervous system abnormalities have now been frequently reported in patients. The cardiac phenotype includes decreased parasympathetic nervous activity and increased sympathetic nervous activity. Currently there is no reliable mode of prenatal diagnosis or cure. For a series of reasons, diagnosis of Duchenne patients using DNA markers from amniocytes is error ridden and deletion mutants are detectable in only 65% of cases. Therefore, early detection of the disease before locomotor or autonomic disturbances reduce quality of life or irreversibly affect outcome of the disease could significantly improve life-quality prospects and longevity in those afflicted with dystrophin-deficiency related diseases.